How quickly should a coolant system become pressurized? The

>>17371227
What engine?

>>17371236
NA miata 1.8

>>17371227
OP, easiest way to check is to stop your engine from firing (e.g. unplugging the ignition coil, pulling the fuel injector fuse, or bridging the starter motor relay) and crank it with the radiator cap off.

Make sure you've got the coolant topped up to the very top of the radiator, then crank the engine.

If your head gasket has failed, the engine will force air into the cooling system and make the coolant come out of the top of the radiator at a pretty steady rate. Really bad cases will shoot coolant out like a geyser, but if it's that bad you should already know because your engine will be running like shit.

>>17371227
In most cars its as soon as the Temp gauge rises out of cold.

You can do a leak down test if you're concerned about head gasket failure.

>>17371227
It'll pressurize when the fluid starts to expand, and it only starts to expand when the engine warms the coolant. So until your engine is at least partially warmed up it won't really be pressurized. If it heats up too quickly there is a hot spot in the system or perhaps an issue with the radiator not functioning properly

Thanks guys.
So it's not unusual for the system to build pressure quickly when the thermostat opens?

I bought a kit that tests for exhaust gas in the coolant system just to be sure.

>>17373953
if there is no excessive smoke coming out of your tailpipe and no schmoo dripping on your block, you're fine

>>17373953
If it builds up enough pressure to make the radiator hoses feel really firm in under, say, 2 minutes when it's cold, I'd be worried.

After 10 minutes of light driving it should have at least a bit of pressure in it, though. What model car is it? Newer cars tend to warm up pretty quickly to help with emissions.